This invention relates to a window shade, and more particularly to a power-operated window shade having rollers at the top and bottom of the window with a flexible film attached to the upper and lower rollers, with the film having selected coatings thereon for varying the reflectivity, transmissivity, or other characteristics of the shade thereby to regulate the amount of light and solar radiation admitted into the room via the window opening, and also to provide privacy and ventilation, as desired, by the occupants of the room.
Generally stated, the window shade of the present invention utilizes an upper and a lower roller assembly, each powered by an electric motor, with the upper and lower rollers having an elongate flexible film of synthetic resin or the like, such as a suitable polyester resin, having a variety of segments thereon, with each segment coated so as to reflect or transmit light either from an outside source (e.g., solar radiation) or from an inside source (e.g., a lamp).
Reference may be made to U.S. Pat. No. 799,123, which discloses a double pane window having a roller shade disposed at the top thereof with the shade extending downwardly between the inner and outer window panes.
U.S. Pat. No. 1,522,352 discloses a structure for a security shutter in which the shutter is furled and unfurled from a roll at the bottom and has a chain and counterweight arrangement for biasing the shutter upwardly. A drive assembly is provided at the end of the roller for furling and unfurling the shutter assembly.
U.S. Pat. No. 1,830,405 discloses a shutter assembly having a winch and cable drive mechanism for opening and closing the shutter.
U.S. Pat. No. 3,186,473 discloses means for controlling the light entering the room comprising a pair of rollers, one at the top of the window and one at the bottom of the window, with an elongate sheet of plastic having a number of panels therein of generally equal length, with the length of each of the panels being somewhat greater than the distance between cross strips at the top and bottom of the window. An electric motor powers the bottom roller, and a hand-operated crank is provided for the upper roller. The rectangular panels may have pictorial scenes printed thereon, and others of the panel may either be transparent or have some light-reducing color or filter media thereon for reducing the amount of light entering the window.
U.S. Pat. Nos. 4,009,745 and 4,042,028 disclose various tube shade rollers having spring return drives.
U.S. Pat. No. 4,172,563 discloses a drive for an awning or roller drive in which a tubular shaft is driven, and upon which is supported a shade to be wound and unwound. The roller is driven by a planetary gear drive located within the shaft or roller.
U.S. Pat. No. 4,346,749 discloses a motor support for a window shade. A spring motor is utilized to wind and unwind the window shade.
U.S. Pat. No. 4,347,886 discloses a roller blind in which a reversible motor drives a roller via a worm gear and sector drive mechanism.
U.S. Pat. No. 4,357,978 discloses a seal system for the edges of a window shade and a seal for the lower edge of the window shade when it is in its lowered position.
U.S. Pat. No. 4,372,367 discloses a roller blind having a reversible electric motor located coaxially with respect to the roller tube.
With the advent of modern curtain wall buildings and contemporary residences having large expanses of window area, it is important to control the amount of solar radiation entering the building through the windows such that in the summertime, air conditioning loads are minimized, and such that during the wintertime, solar radiation may be utilized, as much as possible, to assist in heating the building. Oftentimes, buildings of contemporary architecture utilize a mirrored, reflective glass window so as to minimize transmission of solar radiation into the building, thereby to minimize solar heat loads during the summer months, and thus minimizing air conditioning requirements. While these reflective, mirrored windows work well for minimizing solar radiation heat loads for air conditioning applications, they effectively prevent any solar radiation in heating of the building (even to a limited extent) during the wintertime. Also, with such permanently installed glazed windows, the occupants of the building could not selectively permit additional sunlight to enter the building, or could not ensure total privacy without the addition of interior shades or drapes.
As certain of the above-identified prior art patents have disclosed, it may be advantageous to provide a power-operated window shade arrangement having a variety of different segments on the shade, with each segment having its own reflective characteristics thereby to selectively control the amount of radiaton or light entering or exiting a room thereby to control solar radiation heating effects within the room, and so as to ensure privacy. It has also been recognized that by automatically controlling operation of the window, as by computer control system or the like, the solar heating loads on the building, both during the summer and winter months, can be advantageously controlled so as to minimize air conditioning heat loads, and so as to maximize solar radiation heating during the winter months.
However, there has been a long-standing problem with all such power-operated windows as to how one could effectively and automatically scroll and unscroll the window shade material from the upper and lower rolls in such manner that a wide variety of window lengths can be accommodated, and yet so that under all various conditions, the window shading material would remain taut and free of wrinkles or creases so as to remain substantially imperceptible to the occupants within the building, and so as to create a uniform architectural appearance from the exterior of the building.